A. Field of the Invention
This application relates to the field of correlated golf clubs.
B. Prior Art
The matching of golf clubs is well known in the art and is summarized in Cochran and Stobbs, "The Search for the Perfect Swing", Chapter 33, J. B. Lippincott Co., 1968. This text describes the matching of clubs by the traditional swing-weight method and suggests other techniques. The swing-weight technique is a static measurement in which the club maker places the clubs in a swing-weight balance and reads off a particular number depending upon the scale used. The swing-weight is defined as the moment of the club's weight about a point 12 inches from the grip end of the club. In a particular example, a two iron weighs 15 oz. having a balance point 281/2 inches from the top end of the shaft. The swing-weight is calculated by multiplying the weight by the distance between the balance point of the club and the 12 inch pivot on the scale. Accordingly, the swing-weight is calculated to be 2471/2 ounce-inches. This swing-weight technique is described in detail in U.S. Pat. Nos. 1,953,916 and 1,594,801.
In another matching technique the clubs are matched by matching the moment of inertia of the clubs as described, for example, in U.S. Pat. Nos. 3,473,370; 3,698,239 and 3,703,824. In the moment of inertia technique, the golf clubs are typically dynamically balanced by matching the moment of inertia of each club about its center of gravity or about some other pivot a fixed distance from the butt end of each club.
However, both of these prior techniques have left much to be desired since the total human perception is a blend of both static and dynamic perceptions. Portions of the golf swing are relatively static in nature such as the address and the backswing. The golfer perceives messages from the club through his hands corresponding to the weight of the club and the moment about his grip during these essentially static portions of the swing. On the other hand, other portions of the swing such as the downswing are dynamic. Neither static balancing nor dynamic balancing taken as independent parameters achieves the combined objective of providing the player with a uniformity of feel and balance throughout both the dynamic as well as static segments of the golf swing. A reason why dynamic balancing alone is not sufficient is that when a club is dynamically balanced, during the static portion of the swing it will feel heavier or lighter than another since the golfer is also sensitive to the static weight of the club. It has been found that a golfer's subconscious perception of the static weight of the golf club will affect how he swings the club. If golf clubs feel differently to the golfer, there is a tendency on his part to try to swing them differently. This is described for example, in David Williams, "The Science of the Golf Swing" Chapter 10, Pelham Books Ltd., London, 1969.